A review of superconductivity in nanostructures-from nanogranular films to anti-dot arrays

Superconductivity in small particles has been studied since the early sixties. A large number of sample geometries for both one component elemental superconductors and dual component nano-composites having elemental superconducting particles dispersed in a non-superconducting matrix have been explored which has helped us to understand the mechanism of the evolution of the superconducting transition temperature (T (c)) with decreasing particle size. In this article, we review the work done on nanostructured superconductors from nanogranular films to these dual component superconducting nano-composites. In addition, we also present the experimental work done on another nanostructured system, the superconducting films with periodic arrays of nano-sized holes, showing the interesting property of the vortex matching effect and we try to understand the dominant mechanism for this phenomena.